カプセル内視鏡の現状と展望―診断精度向上の工夫

Improvement of Diagnostic Accuracy of Capsule Endoscopy

要旨　小腸カプセル内視鏡（CE）検査の診断率の向上のためには，リアルタイムビューアーの活用，前処置の工夫，読影精度の向上が要求される．リアルタイムで観察し，食道・胃内にCEがとどまるようであれば，飲水負荷，体位変換，プロカイネティクスの投与や，上部内視鏡による誘導などで対処する．腸管洗浄剤の投与は，回腸遠位側の画像改善に有用であるが，CE検査の受容性を損ねる可能性がある．読影初心者の病変検出率は，読影熟練内視鏡技師と比較して低い．また，有意な病変を見落とさないためには，読影熟練者2人による読影が必要である．画像読影の内視鏡医の負担を軽減し，診断効率を改善するためには，読影技師の育成と精度の高い読影支援ソフトの開発が期待される．

　Use of real-time viewer, appropriate bowel preparation, and reading with increase of diagnosis yield is required for improvement of the diagnostic accuracy of CE（capsule endoscopy）. Use of real-time viewer coupled with a prespecified response（e.g., administration of water, prokinetics, or endoscopic-assisted duodenal placement of CE）to delayed CE transit significantly enhanced completion rate and positive finding rate. Composition of bowel preparation are necessary to provide optimum visualization especially in the distal part of ileum, however it may reduce patients' acceptability. Detection rate by a physician with limited capsule experience is lower than that by well-trained nurse, and evaluation of the capsule video by at least two trained readers seems to be required to prevent overlooking lesions. Training assistants in the reading capsule images and improved reading software could save a great deal of time for physicians and improve diagnostic yield.